Shoe sole with compressible protruding element

ABSTRACT

A footwear sole assembly with at least one compressible protruding element extending downwardly beyond the bottom surface of the outsole, the at least one protruding element providing a natural instability to a wearer when the sole assembly initially contacts a supporting surface. The at least one protruding element is a three-dimensional structure formed of a substantially solid elastomeric material. In another embodiment, the at least one protruding element may also protrude upwardly beyond the sole assembly in such a manner that the wearer&#39;s foot can apply pressure to the top portion of said at least one protruding element.

BACKGROUND OF INVENTION

The present invention relates to a footwear construction and, more particularly, to a footwear sole construction with one or more compressible protruding elements or elastomeric ball-shaped objects.

Numerous attempts have been made over the years to incorporate into a shoe means for providing improved cushioning and resiliency to the shoe. These attempts have included using air cushioning systems such as air cavities or air bladders disposed within the sole of a shoe. However, the conventional cushioning systems only give wearers comfort by cushioning effect.

On the other hand, physical exercise of the foot through ranges of motion and physical stretching have provided for many a modicum of relief. Manual manipulation of an elastomeric member, for example, a rubber ball or stress ball, has proven beneficial to some for muscle toning and/or relief of stress. Furthermore, the benefits of exercising or sitting on a resilient ball, for example, sitting on a fitness ball, are well known. In this regard, the body responds to the instability of the ball and one attempts to remain balanced on the ball thereby engaging many more muscles than normal. Those muscles used to maintain one's balance on the ball become stronger over time. Movement of one's body on the ball changes the center of gravity of the user and causes the user's unused muscles to tighten automatically to maintain balance and stability on the ball.

It would therefore be advantageous to apply the benefits of the stress ball and fitness ball under the foot and develop a footwear platform that both provides comfort and cushioning from impact yet also promotes fitness and muscle toning through normal use. Since a ball is a natural geometric shape that enables multi-axial balance and motion, developing these attributes in a shoe sole would be desirable.

Thus, there exists a need in the art for a system that can be used in footwear to provide natural temporary instability thereby improving balance and muscle tone.

SUMMARY OF INVENTION

The present invention pertains generally to a footwear sole assembly which includes one or more elastomeric compressible protruding elements extending outwardly and downwardly from the outsole of the sole assembly. The sole of a typical shoe generally serves three purposes: cushioning, protection and support. Any one of these functions may be accomplished by numerous materials or structure. The present invention serves an additional purpose of exercising certain muscles of the body by providing a natural instability to a wearer's foot.

The protruding compressible elements of the present invention function as an exercise tool for promoting balance and muscle toning. The present invention promotes balance because when the protruding element first strikes the ground or other walking surface, the shape of the protruding element provides deflection of the user's foot and shoe to one side or the other, such deflection being suitable for short term instability. When the user's foot first comes into contact with the ground or the walking surface, contact is first made between the protruding element and the supporting surface. This impact causes the protruding elements to compress as a reaction to how a user's foot first lands on the supporting surface and creates a temporary instability. The user's body responds to this instability of the protruding compressible elements to remain balanced thereby engaging many more muscles to recover to a normal transition. This compression, deflection and recovery cycle is what creates the workout or exercise system to trim and tone certain muscles.

In one aspect of the present invention, the present invention provides a shoe construction comprised of an arcuate-shaped protrusion projected downwardly beyond the bottom surface of the outsole toward the ground. The protrusion element is a three-dimensional, substantially solid structure formed of a suitable elastomeric material so as to create temporary instability to a wearer of the footwear and to allow the resilient material to be compressed. The protrusion element is physically exposed beyond the outsole.

In accordance with the present invention, the compressible protruding element first comes in contact with the ground or other supporting surface so as to create a natural temporary instability to the wearer's foot. The force of the ground contacting the protrusion and the force of the wearer's heel on the sole assembly and top surface of the protrusion causes the protrusion to be compressed. As the bottom component of the protrusion is compressed, the peripheral edges of the outsole around the protrusion come in contact with the ground so as to provide stability to the wearer's foot during subsequent movement.

Each protrusion element is a partially or substantially ball-shaped object made of any of a number of suitable resilient materials such as foam rubber or plastic. In use, the protrusion element provides a cushioning effect as well as natural instability. The sole assembly comprises at least one protrusion element formed on the bottom surface thereof, extending generally from the heel portion and/or forefoot portion of the outsole. The protrusion element can be designed to follow many geometric shapes, for example, spherical, oval, elliptical and so forth, that can be varied depending on the end use. The protrusion element formed on the bottom surface of the outsole provides the cushioning and deflection suitable for short term instability.

In accordance with the present invention, protrusion elements are affixed to the sole assembly in a variety of different ways. In this regard, each protrusion element may include a peripheral flange extending outwardly from the outer surface thereof. The peripheral flange allows the protrusion element to be secured in proper position within the sole assembly. The protrusion element has a generally round-shaped or elliptical configuration that extends vertically down in the vicinity of the heel and/or forefoot area with the bottom edges thereof tapered downwardly and inwardly, for defining a semi-ball shaped protrusion. The sole assembly, which includes preferably a midsole and an outsole, receives the protrusion element such that the peripheral flange of the protrusion is held in place within the sole assembly, and is preferably disposed between the midsole and outsole. However, other securing means to hold the protrusion elements in place within the sole assembly can likewise be used without departing from the spirit and scope of the invention. Also, the protrusion element can be molded directly into the sole assembly.

Specific advantages and features of the present sole assembly will be apparent from the accompanying drawings and the description of several illustrative embodiments of the present invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of one embodiment of a shoe with compressible protruding elements constructed in accordance with the teachings of the present invention.

FIG. 2 is an exploded perspective view of one embodiment of a shoe showing various components thereof.

FIG. 3 is an exploded perspective view of another embodiment of a shoe showing various components thereof.

FIG. 4 is a fragmentary side view of the present sole assembly showing two compressible protruding elements.

FIG. 5 is a bottom view of the sole assembly of FIG. 4 showing two compressible protruding elements.

FIG. 6 is a fragmentary side view of the present sole assembly showing the use of one compressible protruding element.

FIG. 7 is a bottom view of the sole assembly of FIG. 6 showing one compressible protruding element.

FIG. 8A is a fragmentary perspective view of one embodiment of the present compressible protruding element.

FIG. 8B is a fragmentary perspective view of a second alternative embodiment of the present compressible protruding element.

FIG. 8C is a fragmentary perspective view of a third alternative embodiment of the present compressible protruding element.

FIG. 9 is a fragmentary perspective view of the present compressible protruding element secured within the sole assembly.

FIG. 9A is a cross-sectional view of the present sole assembly with a compressible protruding element taken along line 9A-9A of FIG. 9 wherein the cover layer of the protruding element is associated with the protruding element.

FIG. 9B is a cross-sectional view of the present sole assembly with a compressible protruding element taken along line 9B-9B of FIG. 9 wherein the cover layer of the protruding element is associated with the outsole.

FIGS. 10A-10C illustrate various embodiments of the protruding element construction having a different core member embedded therewithin.

FIGS. 11A-11C illustrate another embodiment of a shoe having an open top shoe and incorporating a protruding element in the heel area.

FIG. 12 is a fragmentary perspective view of an alternative embodiment of the present compressible protruding element shown from the bottom of the outsole.

FIGS. 13A and 13B are perspective views of a sock liner with an opening formed therein.

FIGS. 14A-14C illustrate cross-sectional views of various embodiments of an interchangeable protruding element.

FIG. 15 is a typical force vs. deflection curve for an elastomeric compressible material suitable for use as a protruding element.

It should be understood that the drawings are not necessarily to scale and that the embodiments disclosed herein are sometimes illustrated by fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. It should also be understood that the invention is not necessarily limited to the particular embodiments illustrated herein. Like numbers utilized throughout the various figures designate like or similar parts or structure.

DETAILED DESCRIPTION

A shoe generally includes an upper and a sole assembly that is affixed to the upper. The sole assembly includes an insole, a midsole, and an outsole, each having a peripheral shape designed to conform to the shape of a wearer's foot. To facilitate disclosure of the present invention, reference will be made to various general areas of the foot, such as the heel, arch and forefoot areas. When used to refer to locations on the various sole components, these terms should be interpreted to include those areas of the outsole that are disposed generally (and not necessarily directly) beneath the corresponding elements of the foot. It should be understood, however, that the boundaries between the heel, arch and forefoot areas are not precise and that these terms should be interpreted loosely and with a great deal of flexibility.

The reference numeral 10 designates generally a shoe construction as seen in FIGS. 1-3. Sole assembly 12 generally includes an insole 14, a midsole 16 and an outer sole or outsole 18 which are secured together in any suitable manner such as by a suitable adhesive and the like. Midsole 16 is typically positioned above the outsole 18 and a sock liner 20 is typically positioned above the midsole 16, and above the insole 14 when an insole is used. Insole 14 or some other sole layer component may also be included as one of the various separate sole layers of the shoe. Sock liner 20 typically makes contact with the bottom of the wearer's foot. The various other sole layers are typically disposed between the top surface of the outsole 18 and the undersurface of the sock liner 20. The midsole 16 is typically formed of any suitable material that serves as a cushioning/protection layer. The sole assembly 12 is attached in a conventional manner, such as with an adhesive, or direct injection molding, to an upper 22.

FIGS. 1-3 show a typical shoe 10 which includes an upper 22, a sock liner 20, an insole 14, a midsole 16 and an outsole 18 in a sequence whereby the bottom of the foot makes first contact with the sock liner 20. The sock liner 20 is separated from the outsole 18 by the insole 14 and the midsole 16. At least one protrusion element 24 and 26 is provided to extend or penetrate through the outsole 18 to make direct contact with the ground or other walking surface as illustrated in FIGS. 2 and 3. In a further embodiment as illustrated in FIG. 3, protrusion elements 24 and 26 are provided to penetrate through the midsole 16 to make direct or indirect contact with the bottom of a wearer's foot.

Outsole 18 is generally a thin layer made of a wear resistant material such as high density foam, thermoplastic polyurethane, rubber, a foamed polymer or elastomer, a composite thereof or the like depending upon the type of shoe desired. In another embodiment, outsole 18 may be somewhat thicker. Outsole 18 also has a toe end 28 and a heel end 30. The length and width of outsole 18 are completely dependent upon the size of the shoe onto which the outsole 18 will be placed. Outsole 18 is positioned between the midsole 16, if one is used, and the ground, and forms the ground engaging surface. The outsole 18 has an interior surface 32 which faces the midsole 16 and an exterior surface 33 which is subject to engagement with the pavement or other underlying support surface, which will hereinafter be referred to as the “ground”.

As shown in FIGS. 2 and 3, the midsole 16 is formed with upwardly extending sidewalls 34 that extend around the shoe to define a cavity 36 which is open at the top. The insole 14 is disposed within the cavity 36 and surrounded by the sidewalls 34. The sock liner 20 and lower ends of the upper 22 are disposed within the cavity 36 so that the lower ends of the upper 22 abut the sidewalls 34. The upper 22 is attached to the sidewalls 34. In an exemplary embodiment, the midsole 16 is made of a resilient material, such as ethylene vinyl acetate (EVA) or polyurethane (PU), which provides cushioning and support to the shoe wearer's foot. However, other resilient materials exhibiting similar cushioning and supporting characteristics could be used without departing from the spirit and scope of the invention. The midsole 16 could be constructed as a single molded component or two molded components that are then cemented or otherwise bonded to one another. The thickness of the insole 14, midsole 16, and outsole 18 may be selected to provide the desired combination of wear, resilience, and conformability in a particular sole assembly 12.

The shoe upper 22 can be of any suitable style or shape and includes a foot opening 38 and is shown as having a sidewall to form an enclosed slip-on style top. A sock liner or footbed 20 may be provided that is insertable inside the foot receiving opening 38 of the upper 22 and may be a fabric, coated fabric, leather or other suitable material.

As illustrated in FIGS. 2 and 3, an arcuate-shaped protrusion element 24 and/or 26 is positioned through openings 40 and 42 of the outsole 18 and is projected downwardly beyond the bottom or exterior surface 33 of the outsole 18 adjacent the openings 40 and 42 toward the ground. Protrusion element 24 and/or 26 has a domed bottom surface 44 and a flange 46. As shown in FIGS. 1-3, sole assembly 12 comprises at least one protrusion 24 and 26 formed or otherwise located on the bottom surface thereof, extending downwardly from the heel portion and/or forefoot portion of the outsole 18. The protrusion 24 and/or 26 is a three-dimensional substantially solid structure formed of a suitable elastomeric material so as to create temporary instability to a wearer of the footwear and to allow the resilient material to be compressed when the weight of a wearer is forced thereagainst. The protrusion 24 and/or 26 is physically exposed beyond the bottom surface 33 of the outsole 18. In the embodiment illustrated in FIG. 2, the protrusions 24 and 26 are generally semi-ball shaped as further illustrated in FIG. 8A and include a substantially flat top surface 45 which can mate with either the bottom surface of the midsole 16 or a recessed area associated with the midsole 16. In the embodiment illustrated in FIG. 2, the protrusions 24 and 26 only extend downwardly through the openings 40 and 42, thus the semi-ball or half-ball shape of protrusion elements 24 and 26. In one embodiment, the protrusions 24 and 26 project or extend downwardly from the bottom surface 33 of the outsole 18 a distance H₁ in the range from about 4 millimeters (mm) to about 2 inches (in) as best illustrated in FIG. 9A.

In total contrast, in the embodiment illustrated in FIG. 3, the protrusion elements 24 and 26 are more spherical, oval or elliptical in shape and include a bottom component 44 and a top component 56 wherein the protrusion elements 24 and 26 protrude both upwardly as well as downwardly as illustrated in FIG. 3. The bottom and top components 44 and 56 of the protrusion elements 24 and 26 are illustrated as being substantially dome shaped, the bottom components 44 extending through the openings 40 and 42 associated with the outsole 18 and the top components 56 extending through openings such as the opening 64 associated with the midsole 16 and through corresponding openings such as the opening 66 associated with the insole 14. In this particular embodiment, the top component 56 of the respective protrusions 24 and 26 extend upwardly through the respective openings 64 and 66 to a position adjacent to or slightly through the sock liner 20 in such a manner that the wearer's foot can apply pressure to the top protrusion component 56 when the wearer's foot is positioned on top of the sock liner 20. As will be hereinafter further explained, in this particular embodiment, the sock liner 20 may likewise include corresponding openings as best illustrated in FIGS. 13A and 13B for providing access to the top component 56 of each respective protrusion 24 and/or 26. In one embodiment, the protrusions 24 and 26 project or extend upwardly from the top surface of the midsole 16 a distance H₂ in the range from about 1 millimeter (mm) to about 1 inch (in) as best illustrated in FIG. 9A. Constructions of a suitable protrusion element 24 and/or 26 for use in the embodiment illustrated in FIG. 3 are likewise disclosed in FIGS. 8B and 8C as will be hereinafter further explained. In addition, as will likewise be hereinafter further explained, the protrusions 24 and 26 illustrated in FIGS. 2 and 3 can be utilized as a pair as illustrated in FIGS. 2 and 3, or a single protrusion 24 could be utilized in either embodiment either in the heel portion of the sole assembly or in the forefoot portion of the sole assembly as illustrated.

Each protrusion 24 and 26 may be of any suitable size, shape and depth, the geometry of which can be sculpted to accommodate different gait and exercise characteristics. For example, a substantially flat top surface area can be added to increase the stability of the wearer while curved medial side edges are still preferred for creating natural instability. The leading end of the protrusion can be tapered to provide smooth and stable support for the wearer. The protrusion 24 and 26 can likewise be designed to follow any suitable geometric shapes such as, for example, spherical, oval, elliptical or some other arcuate type shape that can be varied depending upon the end use. As an illustrative example, the protrusions 24 and 26 are generally semi-circular arcuate, semi-elliptical arcuate, or partially or substantially curved arcuate in shape on the bottom surface of the protrusions 24 and 26 when viewed from the bottom surface of the outsole 18. The top surface 56 of the protrusions 24 and 26 in the embodiment of FIG. 3 can likewise be generally semi-circular arcuate, semi-elliptical arcuate, or partially or substantially curved arcuate in shape. The protrusions 24 and 26 formed on the bottom surface 33 of the outsole 18 provide the cushioning and deflection suitable for short term instability. Although the ranges for the distances H₁, and H₂ illustrated in FIGS. 9A and 9B and discussed above can be used in certain embodiments, such distances can vary depending upon the shape, size and style of shoe and depending upon the particular shoe application.

Each protrusion 24 and 26 extends at least from the bottom surface 33 of the outsole 18 and comprises a suitable elastomeric compressible material such as a low-density foam material which is resiliently compressible under an applied load to attenuate ground reaction forces and absorb energy. Protrusion element 24 and 26 can be preferably molded from an elastomeric material such as Polyether Polyurethane, EVA, rubber sponge, solid or foamed elastomer, SEBS and/or TPR gels or dual density Polyurethane. However, it should also be noted that protrusion elements 24 and 26 may also be formed of a molded urethane or any other material having exceptional memory characteristics. In a preferred embodiment, protrusion 24 and 26 is comprised of Polyether Polyurethane of 0.20-0.40 specific gravity, single density and of 25-60° Asker C hardness. One goal includes achieving 50%-60% compression yet allowing immediate recovery of the protrusion element when released from compression. Further, beyond just quick recovery, it is also desirable to achieve total recovery. To achieve this, one goal is to provide for the selection of a peculiarly appropriate foam or compressible material. Regardless of material types, size or shape, the ratio between the force applied and the deflection of the elastomeric material used for the protrusion element should be substantially a straight line that represents a linear response in the deflection range of 0%-50%. That is, the elastomeric compressible material of the protrusion element exhibits a cushion effect that is characterized by a generally linear force versus deflection curve up to about 50% deflection. The slope (stiffness) of the graph can change depending on the material selected for the specific end use, but the material selected should maintain a straight/steady slope through at least 0% to 50% deflection or compression as best illustrated in FIG. 15. The key is to have predictable material properties and performance, regardless of user weight, shoe size, or shape of the protrusion element.

In a preferred embodiment, as illustrated in FIGS. 2 and 3, each protrusion element 24 and 26 is at least partially ball shaped (FIG. 2) and made of any of a number of suitable resilient materials, such as foam rubber or plastic. In an alternative embodiment, the protrusion element 24 and 26 may be made of foams of different densities as illustrated in FIG. 10C. To that extent, the protrusion element 24 and/or 26 can be formed with halves 51 and 53 made or comprised of different materials having different elastomeric properties and/or different hardnesses depending upon the particular application. In addition, the protrusions 24 and 26 may be made of a softer material for enhanced cushioning, while an exterior cover or skin layer 48A or 48B (FIGS. 9A and 9B) may be made of a harder material which is applied to the bottom surface thereof for increased durability when in contact with the ground engaging surface. Unlike the conventional air cavities or air bladders presently is use today, the area within or inside the protrusions 24 and 26 of the present invention is comprised of one or more substantially solid pieces of elastomeric material as illustrated in FIGS. 9A, 9B and 10A-C. In contrast, the conventional air bladder used in many sole constructions utilizes a sturdy or hard material to form the bladder and to avoid a complete collapse of the air bladder, which may actually drain energy from the wearer. Such hard bladder materials reduce flexibility and elasticity. To the contrary, the present protrusions 24 and 26 are formed from a substantially solid piece of elastomeric material, just like the stress ball, and they provide better elasticity without reaching a complete collapse or full compression of the protrusions 24 and 26.

As further illustrated in FIGS. 2, 3, 9A and 9B, midsole 16 and outsole 18 are sized, shaped and joined together to conform around the side portion of protrusions 24 and 26. FIGS. 9A and 9B illustrate a cross-sectional view of a protrusion 24 disposed between midsole 16 and outsole 18. A cover or skin layer 48 of high wear-resistance and non-slip properties can be provided to cover the elastomeric material of the protrusion 24 and 26 for safety, additional traction, and durability of the footwear. In the embodiment illustrated in FIG. 9A, the surface of the skin layer 48A having high wear-resistance and non-slip properties could be a skin layer placed over the bottom portion of the protrusions 24 and 26 themselves and the cover layer 48A could be the same material associated with the outsole 18. Alternatively, the skin layer 48B can be made as a portion of the outsole 18 itself which can include a curved surface extending over that portion of the protrusion 24 which extends outwardly beyond the bottom surface of the outsole 18 as illustrated in FIG. 9B. The skin layer 48 can also have high abrasion and high wet/dry traction and further prevents the protrusion 24 and/or 26 from falling out of the sole assembly. The skin layer 48 can be comprised of compression molded rubber of 0.80-1.0 specific gravity and of 40-75° Shore A hardness. In another embodiment, the skin layer 48 can be formed of TPR, TPU, blown rubber, EVA, PVC, fabric covered polymers, recycled content polymers or any suitable material. The skin layer can be co-molded with the protrusion or cemented onto the protrusion. If not attached to the protrusion 24 and/or 26 as illustrated in FIG. 9A, the skin layer 48 can be attached to the outsole 18 as illustrated in FIG. 9B.

In a further embodiment, the protrusion 24 and 26 can include a core made of another polymeric material to enhance compressive resistance. FIGS. 10A-10C illustrate several embodiments of a protrusion 24 with cores 49 of different shape disposed within the protrusion 24. The protrusion 24 includes a flexible core member 49 which is surrounded or encapsulated by another resilient material. A secondary layer can be added into the protrusion along the bottom surface which provides increased cushioning and performance. The core member 49 can have various shapes such as spherical, oval, rectangular, hexagonal, parallelogram or some other shape. Alternatively, protrusion 24 can be formed with halves 51 and 53 using different materials as previously explained, which construction provides increased cushioning and performance as shown in FIG. 10C.

FIGS. 11A-11C. illustrate an alternative embodiment 10′ of the present invention. The shoe 10′ is generally a women's shoe and includes a heel 72 and an outsole 18. The shoe 10′ includes a shoe top 74 having toe straps 74 and a toe post 78. The shoe top 74 may be secured to the outsole 18 in any suitable manner. The shoe 10′ is provided with a protrusion element 24 formed on the bottom surface thereof extending from the heel 72. The protrusion 24 can be designed to follow many different geometric shapes as previously discussed depending upon the end use. In a preferred embodiment, as illustrated in FIGS. 11A-11C, the protrusion 24 is substantially ball-shaped and made of any of a number of suitable resilient materials such as foam rubber or plastic. In use, protrusion 24 provides a cushioning effect as well as natural instability. In walking and/or running, the bottom surface of protrusion 24 first comes in contact with the ground so as to create a natural instability to the wearer's foot while the heel of a wearer's foot exerts pressure on the top surface of the protrusion 24. In this regard, the top portion 56 of the protrusion element 24 is shown as extending slightly above the heel portion 72. The force of the ground contacting the protrusion 24 and the force of the wearer's heel on the midsole 16 or top component 56 of the protrusion 24 causes the protrusion 24 to be compressed. As the bottom component 44 of the protrusion is compressed, the peripheral edges of the outsole 18 around the protrusion 24 come in contact with the ground so as to provide stability to the wearer's foot.

During walking, running, or other ambulatory activities, the protrusions 24 and 26 initially create temporary instability by the curved surface 44 contacting the ground, and then the protrusions 24 and 26 are compressed between the foot and the ground, thereby attenuating ground reaction forces and reducing the instability as best illustrated in FIGS. 11A-11C. As the wearer steps down, the step is initially unstable due to the curved shape of the protrusion 24 (FIG. 11A) initially contacting the ground and the wearer may use his or her muscles to right his or her position. As more external pressure (i.e. load) is applied as indicated by the arrow L in FIGS. 11A-11C, the protrusion 24 in the region of the external pressure is compressed thereby cushioning the foot as the foot rolls through the typical gait cycle. Full compression of the protrusion 24 is illustrated in FIG. 11C just before the weight of a wearer is transferred to the forefoot of the shoe during a typical gait cycle. When the external pressure is removed, the elastomeric material of the protrusion 24 expands to its original shape.

The protrusions 24 and 26 provide support in the heel and/or forefoot area such that there will be a rocking action of the portions of the outsole 18 and midsole 16 adjacent to the protrusions 24 and 26 during walking and/or running. The protrusions 24 and 26 project from the bottom surface of the outsole 18. In a further embodiment, the outsole 18 may include at least one opening such as the openings 40 and 42 (FIGS. 2 and 3) through which the protrusions 24 and 26 can extend. In a preferred embodiment, the peripheral edge of the opening 40 and/or 42 forms a ring-shaped recess 47 on the bottom side thereof as best shown in FIG. 12. The recess 47 provides space for the protrusion to expand into during compression. The location, size, and number of openings in the outsole 18 or in the sole assembly can be varied depending upon the number of protrusions 24 and/or 26 used in a particular sole assembly as would be readily apparent to one of ordinary skill in the art in order to achieve a desired exercise effect.

The protrusions 24 and 26 are likewise affixed to or otherwise secured to the sole assembly 12 by any suitable means. In the vertical cross section illustrated in FIG. 9A, protrusion 24 has a generally round or elliptical configuration that extends vertically downwardly a distance H₁ with the bottom edges thereof tapered downwardly as best illustrated in FIGS. 8B and 8C. The bottom component 44 of protrusion 24 extends vertically below the annular peripheral flange 46 which functions to hold protrusion 24 and/or 26 in place within the sole assembly 12 as best illustrated in FIG. 9A. The key is to have good securing means for securing the protrusion element 24 and/or 26 between layers of the sole assembly 12. Toward this end, the protrusion 24 and/or 26 includes a peripheral flange 46 extending outwardly from the outer surface thereof. The peripheral flange 46 allows the protrusion 24 and 26 to be secured into position within the sole assembly 12 such as between the midsole 16 and outsole 18. A surface of the peripheral flange 46 of the protrusion 24 and 26 is preferably sized and configured to generally match the contour of the opening 40 and/or 42 of the outsole 18 into which it is mounted and held in place on the upper surface of the outsole 18 along the opening 40 and 42 between the outsole 18 and the midsole 16. However, other securing means to hold protrusion elements 24 and 26 in place within the sole assembly 12 could be used without departing from the spirit and scope of the present invention.

In the illustrated arrangement of FIGS. 2 and 3, outsole 18 and midsole 16 receive protrusion 24 and 26 such that peripheral flange 46 of protrusion 24 and 26 is sandwiched therebetween and held in place within the sole assembly 12, preferably between the midsole 16 and outsole 18, at the interior edge formed by the openings 40 and 42 substantially about the entire periphery thereof. In another embodiment as illustrated in FIG. 9A, there are lower recesses 54 (FIG. 9A) in the forefoot and heel regions of the midsole 16 which receive the peripheral flanges 46 of respective protrusion 24 and 26 above the outsole 18 so that the outsole 18 lies substantially flush against the midsole 16. As shown in FIG. 9A, the shape of each lower recess 54 corresponds to the shape of the peripheral flange 46 of the respective protrusion 24 and/or 26 received in that recess. In this embodiment, the peripheral flange 46 is not visible from a bottom, exterior view of the shoe, but only, from the exploded view. Instead of being molded in one piece and thereafter attached to outsole 18 to accommodate protrusion 24 and 26, midsole 16 may be manufactured with two separately formed foamed layers, and the protrusions 24 and 26 are held in place between these two layers of the midsole 16. Although in the illustrated embodiment of FIGS. 2 and 3, protrusions 24 and 26 are disposed between a midsole 16 and outsole 18, those skilled in the art will appreciate that protrusions 24 and 26 may alternatively be disposed between any layers of the sole assembly 12.

In one embodiment, sole assembly 12 comprises a front protrusion 26 and a rear protrusion 24 projecting downwardly from an outsole 18 as shown in FIGS. 4 and 5. Each of the front and rear protrusions 24 and 26 is compressed by the force or pressure applied in the forefoot and heel areas of the sole assembly 12 respectively. The front protrusion 26 is formed in the vicinity of the forefoot area and the rear protrusion 24 is formed in the vicinity of the heel area. In a further embodiment, the front protrusion 26 and the rear protrusion 24 are similarly constructed, except with respect to the size of each protrusion 24 and 26. The height or depth of the protrusions 24 and 26 may vary depending upon the particular application and the type of shoe involved. Alternatively, sole assembly 12 may include only one protrusion 24 projecting downwardly from an outsole 18 as shown in FIGS. 6 and 7. Although FIGS. 6 and 7 show the protruding element 24 formed or extending downwardly in the vicinity of the heel area, such protrusion could likewise be positioned and located in the vicinity of the forefoot area. It should be obvious to one skilled in the art that the protrusions 24 and 26 can have various configurations and can be positioned in either the forefoot area, in the heel area, in both areas, or anywhere in between the forefoot area and heel area. As would be apparent to one of ordinary skill in the art, sole assembly 12 may be constructed with any number of protrusions without departing from the spirit and scope of the invention.

As can be seen in FIGS. 2, 3 and 8A, each protrusion 24 and 26 defines a partially or substantially convex surface projected beyond the bottom surface of the outsole 18. As previously discussed, the convex or arcuate surface of the protrusions 24 and 26 create instability during use as the arcuate surface of the protrusions 24 and 26 is contacted and compressed during walking or running. The present invention promotes balance of the wearers of such shoes because the ball shaped protrusions 24 and 26 create natural instability and the body responds to the instability of the protrusions 24 and 26 to remain balanced thereby engaging many more muscles. The present invention is specifically configured to increase the muscular workout of certain muscles of the body during walking and/or running thereby increasing muscle tone.

Alternatively, as illustrated in FIGS. 3, 8B and 8C, protrusions 24 and/or 26 include a top component 56 and a bottom component 44 wherein the protrusion protrudes upwardly as well as downwardly. Top component 56 also has a generally tapered upwardly (or inwardly) facing surface which faces a wearer's foot or a sock liner 20 so that the wearer's foot engages the top portion of the protrusion 24 during a typical gait cycle. Bottom component 44 has a downwardly facing surface which faces the ground as previously explained. In a further embodiment, as best illustrated in FIG. 8B, the top component 56 and the bottom component 44 of a particular protrusion element can be formed in two separate components which are thereafter joined together to form a ball shaped object. The top component 56 and the bottom component 44 are connected along a peripheral flange 46. This construction likewise enables the top and bottom portions 56 and 44 to be made of different materials as explained with reference to FIG. 10C. Peripheral flange 46 helps to hold the protrusion 24 in place within the sole assembly 12 and the flange 46 associated with each component 44 and 56 also promotes joinder of the respective components to each other. The bottom component 44 and top component 56 of the protrusion 24 can likewise be formed as a unitary structure having the desired shape via conventional molding techniques as best illustrated in FIG. 8C.

The top component 56 of each protrusion may be curved or circular projecting upwardly a distance H₂ (FIG. 9B) such that an upper portion of the protrusion 24 may bear against the foot of the wearer. In one embodiment, a portion of the protrusion 24 has an indirect contact with the bottom of the foot via a window 58 formed in the sock liner 20. As best shown in FIGS. 13A and 13B, the window 58 preferably includes an opening 60 (FIG. 13A) formed in the heel portion and a fabric material 62 (FIG. 13B) covering the opening 60. The top portion of the top component 56 is disposed over the insole 14 or sock liner 20 and provides a massaging or cushioning effect and further provides comfort to the foot of the wearer. At least one opening 64 and 66 is provided through the midsole 16 and the insole 14 as illustrated in FIG. 3. These openings 64 and 66 are generally aligned with the openings formed on the outsole 18 to allow the protrusions 24 and 26 to extend from the outsole 18, through the midsole 16 and through the insole 14 to the foot of the wearer. These openings 40, 64 and 66 allow for the protrusions 24 and 26 to project upwardly and downwardly beyond the sole assembly. In the embodiment illustrated in FIG. 13A, the top component 56 of the protrusion element is positioned adjacent the opening 60 in such a manner that the wearer's foot can apply pressure to the top component 56. In some cases, the top component 56 may extend through the opening 60 and in some cases the top component 56 may lie flush with or adjacent to the opening 60. In the embodiment illustrated in FIG. 13B, the top component 56 of the protrusion element is positioned and located such that wearer's foot can apply pressure against the fabric material 62 covering the opening 60 and against the top component 56 as previously explained.

The protrusions 24 and 26 may be permanently affixed to sole assembly 12. Alternatively, the protrusions 24 and 26 may be removably detachable from the sole assembly 12 such that multiple sets of protrusions 24 and 26 may be utilized in a single footwear for the same wearer or user. FIGS. 14A-14C illustrate various embodiments of interchangeable protrusion elements 24. In one embodiment, a user, using his or her fingertip, can pry protrusion 24 out of its cavity formed inside the sole assembly 12 after lifting or removing the sock liner (not shown) as illustrated in FIG. 14A. In this embodiment, the skin layer 48 is not cemented to the protrusion 24 for allowing the protrusion 24 to be removed from the sole assembly 12. Once the existing protrusion 24 is removed from the sole assembly 12, the user can insert a replacement protrusion 68 into the cavity by pressing on the top of the replacement protrusion 68. Additionally, the user can step down onto the protrusion to properly seat the protrusion 68.

In another embodiment of a replaceable protrusion element, a pull cord 70 is attached to the core of the protrusion 24 and rests within the shoe as illustrated in FIG. 14B. For replacement of the protrusion, the user lifts and pulls the pull cord 70 located under the sock liner (not shown) to extract the existing protrusion 24 from within the sole assembly. Once the existing protrusion 24 is removed from the sole assembly 12, the user can insert a replacement protrusion (not shown) into the cavity by pressing on the top of the replacement protrusion. The user then lays the pull cord down inside the shoe and steps down onto the protrusion to properly seat the protrusion. Likewise, the skin layer 48 is not cemented to the protrusion for allowing the protrusion to be removed from the sole assembly 12.

Alternatively, a user can heat the sole area of shoe to soften the original adhesive holding a protruding element 24 to detach it from the cavity within the sole assembly 12 as illustrated in FIG. 14C. Once the existing protrusion 24 is removed from the sole assembly 12, the user preheats pressure sensitive adhesive strips 50 associated with the flange portion or other areas of the replacement protrusion before inserting the replacement protrusion into the cavity by pressing on the top of the replacement protrusion. The user then steps down onto the protrusion to properly seat the protrusion and to apply pressure to the pressure sensitive adhesive layer 50 around the edge of the protrusion. Still other replacement methods and means to replace protrusion elements 24 and/or 26 within the sole assembly 12 could be used without departing from the spirit and scope of the present invention.

In order to fully appreciate the cushioning effect of the present invention, the operation of the present invention will now be described in detail. It will be readily seen that the footwear construction of the present invention, because of its unique construction, provides natural instability, thereby requiring a user to exert certain muscles to maintain balance during each walking or running gait cycle. When the wearer begins a stride, the heel area of the footwear contacts the ground or other support surface first. At this time, the weight of the wearer applies downward pressure on the protrusion element causing the protrusion element to be forced downwardly. This impact causes the protrusion element(s) to compress as a reaction to how the wearer's foot lands with respect to the ground (soft/hard, media/lateral, fast/slow) and creates a temporary instability. Certain muscles of the wearer's body then react to this situation and the wearer recovers to a normal transition through the midfoot and toe-off. This compression/deflection and recovery cycle is what creates the workout for the wearer to trim and tone certain muscles.

It is recognized and anticipated that many different variations of the present protruding elements 24 and 26 can be utilized in any particular shoe construction. Although several different styles of shoes and several different embodiments of the various protruding elements and the positioning and location of such protruding elements within a particular sole assembly have been described, any combination of the various embodiments disclosed herein can be utilized in any particular shoe construction. For example, the protruding elements 24 and/or 26 can be used singly or in combination with any particular shoe construction such that a protruding element may extend downwardly from the outsole 18 in the heel area only, in the forefoot area only, or a pair or more of such protruding elements could extend downwardly from the outsole 18 in any particular shoe construction. In one aspect of the present invention, the protruding elements extend downwardly only and do not include a top component 56 for engaging the foot of a wearer. In other embodiments, the protruding elements 24 and/or 26 can be used singly in the heel area only, in the forefoot area only, or a pair or more of such protruding elements could be utilized in any particular shoe construction wherein each protruding element includes a bottom portion 44 and a top portion 56 for projecting both downwardly and upwardly as explained above. It is also recognized and anticipated that some of the protruding elements 24 and/or 26 associated with any particular shoe construction may protrude downwardly only from the outsole 18 whereas other protruding elements may protrude upwardly only so as to engage the foot of a wearer as previously explained. It is also recognized and anticipated that some of the protruding elements associated with a particular shoe construction may protrude downwardly only, some of the protruding elements may protrude upwardly only, and some of the protruding elements may protrude both upwardly and downwardly as previously explained. Still further, it is recognized and anticipated that the top component 56 of the present protruding elements 24 and/or 26 may extend completely through the sock liner for engaging the bottom of a wearer's foot, or such top component 56 may slightly protrude through the opening in the sock liner for engaging the bottom of a wearer's foot, or such top component 56 may lie adjacent to or slightly below the sock liner in a position and location wherein a wearer's foot can apply pressure on the top component of the protrusion element during a typical gait cycle. Other variations and arrangements of the protruding elements are likewise envisioned.

Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present invention will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. 

1. A shoe construction comprising: an upper shaped and sized to receive a foot portion of a wearer; and a sole assembly attached to said upper, the sole assembly including: an outsole; and at least one protrusion extending outwardly from a bottom surface of said outsole, said at least one protrusion being comprised of an elastomeric compressible material, said at least one protrusion having at least partially an arcuate surface.
 2. The shoe construction of claim 1 wherein the sole assembly comprises a first protrusion and a second protrusion, said first protrusion being disposed at a location corresponding to a location where a forefoot of a wearer's foot would sit on said outsole; and said second protrusion being disposed at a location corresponding to a location where a heel of a wearer's foot would sit on said outsole.
 3. The shoe construction of claim 1 wherein said at least one protrusion includes a top component, a bottom component and means for securing said at least one protrusion within the sole assembly, a portion of said top component protruding upwardly beyond said sole assembly, a portion of said bottom component protruding downwardly beyond the bottom surface of said outsole, both said top component and said bottom component having at least partially an arcuate surface.
 4. The shoe construction of claim 1 wherein at least one opening is formed in said outsole, said at least one protrusion protruding through said at least one opening outwardly beyond the bottom surface of said outsole.
 5. The shoe construction of claim 1 wherein said at least one protrusion includes a peripheral flange for securing said at least one protrusion to said sole assembly.
 6. The shoe construction of claim 1 wherein said at least one protrusion includes one or more substantially solid pieces of elastomeric material.
 7. The shoe construction of claim 1 wherein said at least one protrusion has a curved upper surface.
 8. The shoe construction of claim 1 further comprising a sock liner, said sock liner including an opening disposed at a location in registration with the location of said at least one protrusion in such a manner that the wearer's foot can apply pressure on said at least one protrusion through said opening.
 9. The shoe construction of claim 8 wherein said sock liner further includes a thin layer covering said opening.
 10. The shoe construction of claim 1 wherein said outsole includes a recess on the bottom surface thereof along an outer peripheral edge of said at least one protrusion.
 11. The shoe construction of claim 1 wherein the sole assembly further comprises a midsole disposed between the upper and said outsole, said at least one protrusion including means for securing said at least one protrusion between said midsole and said outsole.
 12. The shoe construction of claim 1 wherein said elastomeric compressible material exhibits a cushion effect that is characterized by a generally linear force versus deflection curve up to about 50% deflection.
 13. The shoe construction of claim 1 wherein said at least one protrusion is removably attachable to and removably detachable from said sole assembly.
 14. The shoe construction of claim 13 further comprising a cord affixed to said at least one protrusion in such a manner that said at least one protrusion can be removably detachable from said sole assembly by pulling said cord.
 15. The shoe construction of claim 13 further comprising an adhesive strip attached to said at least one protrusion in such a manner that said at least one protrusion can be removably attachable to said sole assembly with said adhesive strip.
 16. The shoe construction of claim 1 wherein said at least one protrusion is disposed at a location corresponding to a location where a forefoot of a wearer would sit on said outsole.
 17. The shoe construction of claim 1 wherein said at least one protrusion is disposed at a location corresponding to a location where a heel of a wearer would sit on said outsole.
 18. The shoe construction of claim 1 wherein said sole assembly further includes a skin layer positioned beneath said protrusion, said skin layer covering substantially an entire bottom surface of said protrusion.
 19. The shoe construction of claim 1 wherein the bottom surface of said outsole includes a curved surface extending beneath said protrusion, said curved surface covering substantially an entire bottom surface of said protrusion.
 20. The shoe construction of claim 1 wherein said at least one protrusion extends a distance in the range of about 4 mm to about 2 inches between the bottom surface of said outsole and a bottom edge of said protrusion.
 21. The shoe construction of claim 1 wherein said sole assembly includes a midsole disposed above said outsole and said at least one protrusion includes a top component, the top component extending a distance in the range of about 1 mm to about 1 inch between a top surface of said midsole and a top edge of the top component.
 22. A shoe construction comprising: an upper shaped and sized to receive a foot portion of a wearer; and a sole assembly attached to said upper, the sole assembly having a forefoot portion and a heel portion, the sole assembly including: a midsole; an outsole disposed below said midsole; and a first protrusion and a second protrusion, said first protrusion being disposed in the heel portion, said second protrusion being disposed in the forefoot portion, both said first and second protrusions projecting downward from a bottom surface of said outsole, each of said first and second protrusions being comprised of an elastomeric compressible material.
 23. The shoe construction of claim 22 wherein at least one of said first and second protrusions includes a top component, a bottom component and means for securing said protrusion within said sole assembly, a portion of said top component protruding upwardly beyond the sole assembly, a portion of said bottom component protruding downwardly beyond said outsole, both said top component and said bottom component having at least partially an arcuate surface.
 24. The shoe construction of claim 22 wherein said outsole includes a first opening and a second opening, said first protrusion protruding through said first opening outwardly beyond said outsole and said second protrusion protruding through said second opening outwardly beyond said outsole.
 25. The shoe construction of claim 22 wherein at least one of said first and second protrusions includes a peripheral flange for securing said protrusion between said midsole and said outsole.
 26. The shoe construction of claim 22 wherein at least one of said first and second protrusions includes one or more substantially solid pieces of elastomeric material.
 27. The shoe construction of claim 22 wherein at least one of said first and second protrusions has a curved upper surface.
 28. The shoe construction of claim 22 further comprising a sock liner, said sock liner including at least one opening disposed at a location in registration with at least one of said first and second protrusions in such a manner that the wearer's foot can apply pressure on at least one of said first and second protrusions through said at least one opening.
 29. The shoe construction of claim 28 wherein said sock liner further includes a thin layer covering said at least one opening.
 30. The shoe construction of claim 22 wherein said outsole includes a recess on the bottom surface thereof along an outer peripheral edge of at least one of said first and second protrusions.
 31. The shoe construction of claim 22 wherein said elastomeric compressible material exhibits a cushion effect that is characterized by a generally linear force versus deflection curve up to about 50% deflection.
 32. The shoe construction of claim 22 wherein at least one of said first and second protrusions is removably attachable to and removably detachable from said sole assembly.
 33. The shoe construction of claim 32 further comprising a cord affixed to at least one of said first and second protrusions in such a manner that said protrusion can be removably detachable from said sole assembly by pulling said cord.
 34. The shoe construction of claim 33 further comprising an adhesive strip attached to at least one of said first and second protrusions in such a manner that said protrusion can be removably attachable to said sole assembly with said adhesive strip.
 35. The shoe construction of claim 22 wherein said sole assembly further includes at least one skin layer positioned beneath at least one of said first and second protrusions, said at least one skin layer covering substantially an entire bottom surface of said at least one protrusion.
 36. The shoe construction of claim 22 wherein a bottom surface of said outsole includes a curved surface extending beneath at least one of said first and second protrusions, said curved surface covering substantially an entire bottom surface of said at least one protrusion.
 37. The shoe construction of claim 22 wherein at least one of said first and second protrusions extends a distance in the range of about 4 mm to about 2 inches between a bottom surface of said outsole and a bottom edge of said at least one protrusion.
 38. The shoe construction of claim 22 wherein at least one of said first and second protrusions includes a top component, the top component extending a distance in the range of about 1 mm to about 1 inch between a top surface of said midsole and a top edge of the top component.
 39. A shoe construction comprising: an upper shaped and sized to receive a foot portion of a wearer; and a sole assembly attached to said upper, the sole assembly including: an outsole including at least one opening; and at least one substantially solid protruding element extending outwardly from a bottom surface of said outsole through said opening, said at least one protruding element being formed of at least one elastomeric compressible material, said at least one protruding element including a ground engaging surface having at least partially an arcuate shape.
 40. The shoe construction of claim 39 wherein the sole assembly comprises a first protruding element and a second protruding element, said first protruding element being disposed at a location corresponding to a location where a heel of a wearer's foot would sit on said outsole, and said second protruding element being disposed at a location corresponding to a location where a forefoot of a wearer's foot would sit on said outsole.
 41. The shoe construction of claim 39 wherein said at least one protruding element comprises a top component, a bottom component and means for securing said at least one protruding element within the sole assembly, a portion of said top component protruding upwardly beyond the sole assembly, a portion of said bottom component protruding downwardly beyond the bottom surface of said outsole, both said top component and said bottom component having at least partially an arcuate surface.
 42. The shoe construction of claim 39 wherein said at least one protruding element includes a peripheral flange for securing said at least one protruding element to said sole assembly.
 43. The shoe construction of claim 39 wherein said at least one protruding element has a curved upper surface.
 44. The shoe construction of claim 39 further comprising a sock liner, said sock liner including at least one opening disposed at a location in registration with said at least one protruding element in such a manner that the wearer's foot can apply pressure on said at least one protruding element through said at least one opening.
 45. The shoe construction of claim 44 wherein said sock liner further includes a thin layer covering said at least one opening thereof.
 46. The shoe construction of claim 39 wherein said outsole includes a recess on the bottom surface thereof along an outer peripheral edge of said at least one protruding element.
 47. The shoe construction of claim 39 wherein the sole assembly further includes a midsole disposed between the upper and said outsole, said at least one protruding element including means for securing said at least one protruding element between said midsole and said outsole.
 48. The shoe construction of claim 39 wherein said elastomeric compressible material exhibits a cushion effect that is characterized by a generally linear force versus deflection curve up to about 50% deflection.
 49. The shoe construction of claim 39 wherein said at least one protruding element is removably attachable to and removably detachable from said sole assembly.
 50. The shoe construction of claim 49 further including a cord affixed to said at least one protruding element in such a manner that said protruding element can be removably detachable from said sole assembly by pulling said cord.
 51. The shoe construction of claim 49 further including an adhesive strip attached to said at least one protruding element in such a manner that said at least one protruding element can be removably attachable to said sole assembly with said adhesive strip.
 52. The shoe construction of claim 39 wherein said sole assembly further includes a skin layer positioned beneath said at least one protruding element, said skin layer covering said ground engaging surface.
 53. The shoe construction of claim 39 wherein a bottom surface of said outsole includes a curved surface extending beneath said at least one protruding element, said curved surface covering said ground engaging surface.
 54. The shoe construction of claim 39 wherein said at least one substantially solid protruding element extends a distance in the range of about 4 mm to about 2 inches between a bottom surface of said outsole and a bottom edge of said at least one protruding element.
 55. The shoe construction of claim 39 wherein said sole assembly includes a midsole disposed above said outsole and said at least one substantially solid protruding element includes a top component, the top component extending a distance in the range of about 1 mm to about 1 inch between a top surface of said midsole and a top edge of the top component.
 56. A shoe construction comprising: an upper shaped and sized to receive a foot portion of a wearer; and a sole assembly attached to said upper, the sole assembly including an outsole having an opening disposed at a location corresponding to a location where a heel of a wearer's foot would sit on the outsole; and a resilient ball-shaped element extending downwardly from a bottom surface of said outsole through said opening, said ball-shaped element being formed of at least one elastomeric compressible material and including a ground engaging surface having at least partially an arcuate shape so as to create a temporary instability to the wearer of the shoe construction when said ball-shaped element initially contacts a supporting surface, and securing means to secure the ball-shaped element within said sole assembly.
 57. A shoe construction comprising: a sole assembly having a heel portion and a forefoot portion wherein said sole assembly including an outsole; and a substantially solid protruding element disposed in the heel portion, the protruding element projecting downwardly from a bottom surface of said outsole, the protruding element being formed of at least one elastomeric compressible material and including a curved ground engaging surface, said protruding element including securing means to secure the protruding element to said sole assembly. 